Our preliminary study has, for the first time, imaged myofascial taut bands based on their stiffness values. This was accomplished using the Magnetic Resonance Elastography (MRE) technique. The goal of this application is to further test our hypothesis that MRE stiffness measurements of myofascial taut bands are reliable and sensitive to changes resulting from myofascial manual therapies. If the MRE technique is reliable and sensitive, it can be used to assess the efficacy of manual therapies in future studies. The current study will address the following specific aims: Specific Aim 1: To determine the reliability of MRE stiffness measurements of myofascial taut bands and their surrounding muscle tissue. Forty subjects with upper trapezius myofascial pain (as determined by clinical examination and history) and at least one taut band on MRE will be studied. An initial MRE examination will characterize the myofascial taut bands (location of the taut band in the MRE stiffness image, area of the taut band, and stiffness ratio between the taut band and the surrounding muscle tissue). Subjects will undergo a second MRE examination two hours later and the measures statistically compared to determine reliability. Pain will be quantified with an electroalgometer and pain VAS score before and after the second MRE;the change scores from this Aim will be used as a control group in Aim 2. Specific Aim 2: To determine the sensitivity of MRE stiffness measurements to change in a pain visual analog scale (VAS) as a result of Trigger-point Pressure Release therapy. Forty subjects with upper trapezius myofascial pain will be assessed using MRE. The overall muscle stiffness of the upper trapezius as well as the mechanical characterization of taut bands identified in MRE images (size and location of the taut band area and stiffness ratio) will be quantified. Tenderness will be evaluated by a physician using an electroalgometer and a pain VAS scale. Subjects will then be treated with a single treatment with TPR therapy. Pain will be reevaluated by the same individual and stiffness of the upper trapezius will be again measured with a second MRE. To test our hypothesis (that MRE taut band measurements are sensitive to changes resulting from therapy, as indicated by reduced pain score), associations between changes in pain VAS and changes in the MRE parameters of the taut bands will be statistically determined. PUBLIC HEALTH RELEVANCE: Myofascial pain syndrome is a painful and often disabling condition. The exact benefits of manual therapies for myofascial pain remain unknown largely because there are no proven methods of detecting and measuring stiff, painful areas in muscles. Magnetic Resonance Elastography is able to image and measure muscle stiffness and therefore is a promising technique to accurately detect changes in stiff taut bands and trigger points after manual therapy treatment.